The present invention relates to a computer apparatus that communicates on a network, and more particularly to a computer apparatus connectable with a wireless LAN.
A computer apparatus represented by a notebook type personal computer (note PC) is connected to a network such as a LAN (Local Area Network) through an interface unit called an NIC (Network Interface Card) or a LAN adapter. The interface unit connected to the network was a modem at the beginning, but at present, the wire telecommunications such as a token ring (Token-Ring) or the Ethernet (trademark of Xerox, United States) are the mainstream. In the future, the spread of wireless LANs is predicted in order to avoid complex cable wiring, along with the rapid developments of the note PC, portable telephone and mobile terminal such as a PDA.
Herein, for a portable type computer apparatus that is employed while traveling such as the note PC or mobile terminal, it is required for the apparatus to connect to a network at each transfer site. Since the network environment is generally varied for each transfer site, first of all, the portable type computer apparatus has preferably a plurality of network adapters to enable the connection at each transfer site. Also, it is effective to select a network adapter usable at the site from among the plurality of network adapters provided, and make the suitable network settings for the network adapter at the site.
Though this invention is not directly concerned, one of the prior arts associated with the wireless LAN system is an access point device with the enhanced security level, and its approval method, see Published Unexamined Patent Application No. 2001-345819 (pages 4 and 5, FIG. 1).
However, when using a conventional operating system (OS), where a system has a plurality of network adapters, there was no explicit meansra for designating which network adapter to use to make the connection to the network. That is, in the conventional operating system, a desktop type PC in which no movement of location is supposed or anticipated is kept in mind, and there is almost no need or requirement for designating which network to select to make the connection. Therefore, it was required to switch the network by physical means of removing the network adapter or network cable to designate the connection using the conventional system.
Also, in the conventional operating system, one network adapter allowed only one network connection to be set up. Particularly in the mobile specifications for mounting on the note PC or the like, when one network adapter was shared between office and house, which have different settings, it was required to take the effort and trouble to change the network settings every time a network connection was initiated. Also, it is especially difficult to set up the network for the beginner user, and since there appears successively new networks such as a wireless network, a VPN (Virtual Private Network) and a broad band connection or network, it is more complex and difficult for the user to configure and make the network connection.
In the light of this problem, a technique or method has been offered in Japanese Patent Application No.2002-27459 in which the network name of access point is detected through the use of an application and the settings and configuration of a network such as a wireless LAN are automatically performed. This offered technique is superior in that the user can make the network settings automatically at anytime, and easily make the connection to the network. However, from the point of view from the security, a new demand arose for allowing the connection to the access point even when the network name of access point is hidden or unknown.
On the other hand, in the adapter of wireless LAN, it is required to scan all the channels to be supported periodically to find the access point for connection. At this time, when employing a dual mode wireless LAN adapter for handling a 802.11b base wireless network and a 802.11a fast wireless LAN, the number of supported channels (a total of 46 channels) is greater than the conventional 11b single mode adapter. Though an active scan (active search: scan method for sending a probe frame from the mobile terminal and searching for an access point upon its response) was performed in the 802.11b single mode adapter, a passive scan (passive search: scan method for monitoring a beacon signal sent from the access point for a fixed period of time) was made to support the world wide roaming in the dual mode wireless LAN adapter.
Owing to this reason, it takes about 100 seconds to make one channel scan by the dual mode wireless LAN adapter. This scan time is significantly longer than the existent 802.11 b in which the scan time is only about 2 seconds. While this channel scan is being made, the wireless client cannot enter a power saving mode such as a suspend state, increasing an average power consumption by the apparatus and thus, shortening useful operation while under battery power.
FIG. 13 is a chart showing variations in power consumption in the dual mode wireless LAN adapter. In FIG. 13, the axis of abscissas is the time (sec), and the axis of ordinates is the power consumption (W). Herein, a scan of 100 seconds and a power down of 60 seconds are repeated, in which 1 W for the scan of 100 seconds and 0.07 W for the power down of 60 seconds are consumed. Consequently, the average power consumed by a wireless LAN device may reach 650 mA in the example as shown in FIG. 13. In this case, the battery time of the note PC is shortened by 30 minutes or more.
This invention has been achieved to solve the above-mentioned technical problems, and it is a purpose of the invention to allow a connection to an access point in an optimal time even when a network name of the access point is hidden.
Also, it is another purpose of the invention to further reduce power consumption in a computer apparatus with a connection function to the wireless LAN.